Browsing by Author "Tiemann, Paula"

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    Multi-finger synergies and the muscular apparatus of the hand
    (2018-03-12) Cuadra, Cristian; Bartsch, Angelo; Tiemann, Paula; Reschechtko, Sasha; Latash, ·Mark L.
    We explored whether the synergic control of the hand during multi-finger force production tasks depends on the hand muscles involved. Healthy subjects performed accurate force production tasks and targeted force pulses while pressing against loops positioned at the level of fingertips, middle phalanges, and proximal phalanges. This varied the involvement of the extrinsic and intrinsic finger flexors. The framework of the uncontrolled manifold (UCM) hypothesis was used to analyze the structure of inter-trial variance, motor equivalence, and anticipatory synergy adjustments prior to the force pulse in the spaces of finger forces and finger modes (hypothetical finger-specific control signals). Subjects showed larger maximal force magnitudes at the proximal site of force production. There were synergies stabilizing total force during steady-state phases across all three sites of force production; no differences were seen across the sites in indices of structure of variance, motor equivalence, or anticipatory synergy adjustments. Indices of variance, which did not affect the task (within the UCM), correlated with motor equivalent motion between the steady states prior to and after the force pulse; in contrast, variance affecting task performance did not correlate with non-motor equivalent motion. The observations are discussed within the framework of hierarchical control with referent coordinates for salient effectors at each level. The findings suggest that multi-finger synergies are defined at the level of abundant transformation between the low-dimensional hand level and higher dimensional finger level while being relatively immune to transformations between the finger level and muscle level. The results also support the scheme of control with two classes of neural variables that define referent coordinates and gains in back-coupling loops between hierarchical control levels.
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    The impact of the learning environment sudden shifts on students’ performance in the context of the COVID-19 pandemic
    (2023-02-13) Pérez, Miguel A.; Tiemann, Paula; Urrejola-Contreras, Gabriela P.
    Introduction This study aims to determine the effect of sudden changes in learning environments on students’ performance, in the context of the COVID-19 pandemic lockdown. We present an analysis of the kinesiology program, focusing on the learning modality changes through the years, and its impact on students’ performance. Methods We analyzed three periods over five years. During the Pre-pandemic period (2018-2019), classes had been taught in-person, during the pandemic (2020-2021) classes had been taught online, and during end of lockdown (2022) classes had return to in-person modality. In addition, we also examined the academic performance outcomes by gender during the three periods. Results We found that the academic performance significantly increased in all cohort of career, increasing the average grade from 4.7 ± 0.08 (2018 to 2019, in-person) to 5.15 ± 0.07 during the pandemic period, from 2020 to 2021, when online modality was utilized. Furthermore, when returning to in-person classes in 2022, the academic performance reduced significantly to 4.6 ± 0.17. We also found that gender did not have an influence on academic performance in any of the learning environments presented. However, during clinical internships, we found that gender had a significantly effect on academic performance. Conclusion Based on these results, we conclude that the sudden shift from in-person learning to online learning modality helped improved the learning performance of student, reflecting those results on better students’ performance scores that could be associated with the enhanced efficient use of time.